Are Prepared Foods Making Us Fat?

Michael Pollan's
article
on how American cooking "became a spectator sport" should be a wake-up call to young adults, particularly young adults with children. As the article points out, Americans are fascinated by shows about cooking, but show little interest in cooking themselves; instead they are buying more and more fast food and prepared or semi-prepared meals.

The author ties the decline in cooking to more women working outside the home, extensive marketing by food companies to change the social norm so that it becomes acceptable to outsource some or all food preparation for a meal, and the introduction of technology (large freezers, microwaves) that makes it easier to prepare meals. He also ties the rise in purchasing prepared food to the increase in obesity.

As an obesity researcher, I think all of these arguments make sense, but I also know that the data are lacking to make draw firm conclusions. It is true that during the past several decades there has been
an increase
in the amount of prepared food consumed either at home or in restaurants, and a staggering rise in obesity among
children
and
adults
.

Getting people to change what they eat is much harder if they don't cook in the first place.

However, just because two trends occur at the same time does not mean they are related. What is needed are studies that track people's dietary habits and weight over time. So far these studies have shown that
fast food intake
is tied to weight gain. But studies are lacking on the association between other types of prepared foods and weight gain or obesity.

It is a topic I am pursuing, and I continue to be surprised at the dearth of studies. Barbara Rolls and colleagues have shown that portion size influences caloric intake; because prepared foods are often served in large portions, it seems likely that they promote excessive caloric intake and weight gain. But we need more research to make the connection between prepared foods and weight gain.

Further complicating the picture is the huge number of foods that fall under the term "prepared" or "semi-prepared"--and because people are cooking less and less, their very idea of what a prepared food
is
may be changing. Putting pasta sauce from a jar on cooked spaghetti may or may not be considered using prepared foods, depending on the perspective of the "cook."

Further complicating things is the many foods like macaroni and cheese that can be made at home either from scratch or from a mix--or bought as a ready-to-eat dish. Unfortunately, most epidemiologic studies that follow people's diets and weights over time don't collect the details that would allow the authors to differentiate between what was made from scratch and foods at least semi-prepared outside the home. This may explain why there is so little research on the association between prepared foods and obesity.

Alison E. Field is an Associate Professor of Pediatrics at Harvard Medical School and an Associate Professor in Epidemiology at the Harvard School of Public Health. She researches the causes and consequences of weight gain, obesity, weight cycling, and eating disorders in children, adolescents, and adult women. She has been widely published in medical journals, including Pediatrics, Obesity, Archives of Internal Medicine, and has discussed her research on CNN, Fox, and local news affiliates.